The invention relates to an assembly and method of holding plastic film within a mold.
In-mold decorating is a term of art describing the process of applying a decorative coating to a plastic part during the molding process. Conventional methods of applying a decorative coating include the use of a paint film placed within the mold that adheres to a plastic substrate injected into the mold during the molding process. A currently known alternative to the use of paint film is the use of a plastic film. The use of plastic film provides several advantages over the use of paint film. The plastic film can stretch to a greater extent than plastic film, allowing application to complex and intricate shapes. Further, plastic film provides the same color matching capabilities as do paint films. Finally, plastic film is formed of substantially the same base material as the substrate so removal of the plastic film is not required prior to recycling, as is required for paint based films.
Although plastic film includes many advantages over the use of paint films, the use of plastic film presents several design and processing challenges. Typically, plastic film includes at least three layers, a clear layer, a color layer and a substrate layer. The plastic film may include additional layers depending on the composition of the molded article to which the plastic film is adhered. The plastic film must be secured within the mold with sufficient force to prevent movement during molding at pressure, while not crushing the plastic film and the color layer. Crushing of the color layer may cause discoloration and tearing of the plastic film.
Accordingly, it is desirable to develop an apparatus and method of holding the plastic film within the mold with sufficient force to secure the plastic film in place against high molding pressure without causing damage to the plastic film.